Electric fuse socket



Oct. 22, 193s. L, SCHWDT, 5R 2,018,323

ELECTRI C FUSE SOCKET Filed NOV. 5, 1928 2 She'etS-Sheet l Oct. d22, 1935. L. SCHMIDT, JR 2,018,323

ELECTRIC FUSE SOCKET Filed Nov. 5, 1928 2 Sheets-Sheet 2 30 fz J1 14 Je wie "-27- Patented 01m22.193s

PATENT OFFICE 2,018,323 ELEcTaic FUSE sooner- Lamborz schmidt, Jr., Brooklyn, N. Y., miglior` to himself, and Louis Freund, New York, N. Y. e

Appuoouon November 5, 192s, serial No. 311,227

19 claims. (CL zoo-119) My invention relates to electric fuse sockets, and its principalobjects are:

To provide an adapter which enables a small size plug to be inserted in a standard socket, and means for locking-the adapter in position, so that thereafter large size plugs cannot be inserted;

` and to reduce the possibilities of tampering with The circuit breaking device is preferably soA constructed or arranged that it is easily placed in a socket of ordinary construction. i

The characteristics and advantages of the invention are further sufciently explained in connection with the following detail description of the accompanying drawings, which show certain exemplifying embodiments. After considering these examples, skilled persons will understand that many variations ymay be made, and I contemplate the employment of any structures that are properly withinA the scope of the appended claims. f

In the drawings:

Fig. l isa vertical (axial) section o f a socket structure, embodying the invention. in one form.

Fig. 2 is a perspective view of a spring contact operating device. Y

Fig. 3 is a plan view of a movable contact disc and its contact.

Fig. 4 is a vertical axial sectionot a socket arranged for a -plug adapter, and one suitable locking adapter, constituting a part of my invention, inserted therein.

Fig. 5 is a side elevation of the adapter, with a A part in section.

Fig. 6 is a top plan of the same.

Fig. '7 is a section of astandard socket and plug in cooperation with a locking adapter including a movable contact device, and constituting another embodiment of the invention.

Fig. 8 is a side and sectional view of the adapter of Fig. 7.'

Fig. 9 is a bottom plan of the same, with a part in section.'

1n all the examples shown, I is the insulating body (such as porcelain) of a standard electric socket, used for the purposes of this invention as a fuse (or cutout) socket to receive any known or suitable fuse plug 2. The socket body in- 5 cludes a base 3, and a socket or 'sleeve portion l which is open at one side, as at 5. In this sleeve is the metal shell 6 constituting the outer plug contact. This shell is pressed to screw thread formation 1, has an inturned base flange 8 rest- 10 ing on the bottom of the insulator sleeve, and is cut away'at one side, this cut-out or 'slot 9 being positioned in sleeve opening 5. A conducting strip I0 passes through slot 9 and rests on shell flange 8, the outer end of this strip going to, or constituting one of the circuit terminals I I. The center contact of the socket is the head I2 of a screw I3, which passes through a hole Il in body I and engages in a conducting strip I5 which leads to, or constitutes, the other circuit terminal zo I6. A disc II of insulating material is held down by a screw head I2 upon a circular boss I8 of the base and upon conductor strip I0.

The fuse plug 2, in the form shown, has a body of insulating material threaded as at 2I, and 25 the outer contact, for electrical connection with shell 6 is a threaded metal segment 22; the center contact 23, of usual type, in ordinary practice, engages screw headv I2 to complete the circuit through the fuse (not shown) located within a0 the plug in the usual way. Any other suitable type of fuse plug may be employed, and the plug and socket, per se, do not i'orm parts of my invention, except as modiiied in accordance with the invention, or in cooperation with novel i'eal5 tures thereof, as now to be iully explained.

It is now customary to furnish fuse plugs having threaded portions of different diameters, sufciently identified hereafter as "large" and small plugs (or threaded portion diameters). 0 these corresponding, lfor example, to fuse amperage capacities above and below a certain value: and sockets are provided, having "shells" of corresponding diameters; the 'invention includes adapters which may be inserted in the large size sockets, together with means for locking them in position, so that after insertion of the adapter. only a small size plug can be inserted therein, thus properly Ilimiting the current iiow through the particular socket, under control o! compe- 5o tent electricians.

Fig. 1 shows any ordinary plug 2 inserted in a properly dimensioned shell 6 without an adapter, while Figs.-4 and 7 each shows an adapter inserted in the socket shell, thereby enabling the use thereengagement with the socket shell), reverse rotation, or unscrewing, and removal by unauthorized persons; so that, forerample, an electrician may insert the adapter' ina standard or oversize socket and thereafter a standard or oversize 'plug can- ,f not be inserted', but a small siz plug, having a properly predetermined current capacity, must be used.

In all of Figs. 1, 4 and 7, a movable circuit breaker or contact carrier and center contact,

I carried thereby, is included; in Figs. 1 and 4, this device is arranged in or as a part of the socket; while in Fig. '7 the movable contact device is arranged in and as-a part of the adapter.

Referring now to Figs. 1, 2 and 3, in which any standard plug 2 is inserted directly in socket shell S, without an adapter.

A movable contact carrier is located in the lower (inner) part of the shell and may in some cases, as here shown, be removable; otherwise v it may be secured against removal by studs or lugs 26 punched in the shell wall, or otherwise, as explained in connection with Fig. 7. 'I'his contact carrier is of any suitable insulating material, such as synthetic resin composition, hard rubber, bone, etc., and is in the form of a round disc, preferably having a concave upper surface 21, and also a. peripheral wall or ange 28 on its lower face, to cooperate with actuating members (presently referred to) and also forming a chamber for a part of the metal contact. This center contact 29 is located in the center of the carrier, and conveniently is practically in the form of a special stud or rivet, including a stein 30 passing through the carrier disc,l a lower head 3|, located at the under face of the carrier and adapted for contact with the center socket contact I2, and another, small, head or flange 32 formed by. upsetting the end of the stem, to retain the contact in position.

Cooperating with this contact device is an actuator, in the form of a resilient device tending normally to hold theA contact disc in an upward (or outward) position, with head 3| of the contact out of engagement with the socket center lcontact I2, but permitting the disc to move down (or inward) by engagement with contact 32 of the center contact 23 of the plug, in the act of screwing in the plug, thus establishing the center circuit from socket contact I2 through movable contact `29 to the plug contact/2 3.` Specifically, as here shown, this actuating device conl sists of a, flat ring 35 of suitable resilient metal,

- located on the insulating disc |'I of the socket,

surrounding center contact I2, thereof, and so dimensioned that it cannot establish connection between such contact I2 and the shell 8. 'I'his ring has a plurality of integral spring iingers 36, bent up from the normal plane of the ring, and engaging with the under face of disc 25, or speciilcally, with peripheral wall 28 thereof. Thus, when plug 2 is not in the socket, the spring fingers hold the disc in an upward (or outward) position, with contact 3| .out of engagement with socket contact I2; the socket contacts therefore cannot be bridged, to close the circuit, by any l lordinarily available means; since for such unauthorized bridging, it is necessary not only to electrically connect the center contact 32 to shell 6, but to hold the circuit breaker down against in oi' a plug of smaller thread-diameter than the force of its spring; and such manipulation is impracticable to persons of ordinary skill or with ordinarily available devices.

When plug, 2 is inserted, its center contact engages movable contact 29 and moves the disc and said contact down to engagewith socket contact l2 and to complete the circuit in the ordinary and proper way.

The concave, or cupped shape of the outer face of the contact disc 25 also prevents bridging the circuit, whether the disc is in open or closed circuit position, by insertion of any simple or easilyobtained metal piece, such as a coin, since while such object may be made to engage with the sneu wa11,1t will not engage with the enter contact 32, located at the bottom of the epression 21.

In Fig. 4, an adapter 40 is inserted in socket shell 6, for purposes above explained.r 'I'his adapter may be a simple, short, pressed or threaded 20 metal shell dimentioned externally to fit the socket shell, and internally toflt the plug thread; while the latter is of such dimension that in absence of the adapter, it cannot be engaged with the socket shell thread.

26 Preferably, as above stated, the adapter has a locking device, consisting speciiically, as shown, of a wire 4| of stili, spring metal (see Figs. 5 and 6, and also Fig. 9, which shows substantially the same locking arrangement). This wire is located at the bottom of one of the adapter threads (or grooves) and secured by passing it through two or more perforations 42 in the adapter shell, which may then be pressed to retain the wire in position. -One end 43 oi' the wire is bent outward, and its end constitutes in effect a pawl or detent, which, when the adapter is screwed into the socket shell, slides freely in contact withI the shell surface; but upon any force being applied to rotate the adapter reversely, this detent or prong bites into the socket shell, and prevents such rotation, and removal of the adaper. Therefore, when once inserted, only plugs of predetermined dimension, and' amperage" can be inserted in the socket..

In Fig. 4, the adapter may serve to prevent removal of the circuit breaking device, disc 25 being of such diameter that it cannot be brought up through the adapter.

In Figs. 7,` 8 and 9, the movable contact device is located in the adapter, instead of in the socket. The adapter and its detent device may be as above described, except that the adapter body, or shell 50, is longer, having a lower (or inner) cylindrical portion 5| of somewhat reduced diameter, terminating in' an inturnedfflange 52. The movable contact disc 25 is located in the cylindrical lower portion 5| of the adapter, and the actuating ring 53" rests on ange 52, with its spring fingers 36 tending to support the contact disc and maintain contact 3| out of en- Asocket shell.

' The adapter of Fig. 7 also has a locking, or detentl device 4| substantially similar to that described in connection with Fig. 4 (see also Figs. 8 and 9), the detent wire being in this case located above the movable contact chamber, and

aoliasas' at the lower end of the threaded portion of the shell. 1

Inbothoflligs.1and4,thesidewallof the contact carrier 2,5 is so dimensioned or arranged that it is impossible or impracticable to short" the socket contacts by ,a metal piece inserted through the shell slot whereas in absence of this protective feature, such tampering is relatively easy.l

In Fig. 7, the same by the lower part of the adapter, which partly or entirely blocks o the shell slot l, at its inner side.

I claim:`

l. An adapter for an `electric or fse socket. comprising a threaded metal shell insertible in the socket shell, and adapting it to receive a small size plug, and a detent device in the adapter cooperating with the socket shell, to permit inscrewing of the adapter. and prevent outscrewing thereof, said detent consisting of a spring wire inserted through the adapted wall and having a resilient point to engage the socket shell.

2. For use in an electric fuse socket having a shell and a center contact, a contact carrier arranged for axial movement within the shell and having a central contact piece to connect the center contact of a plug with the center contact of the socket, means for causing movement of said contact carrier in one direction, and means for hunting the movement of said contact carrier away from said center'contact.

3. For use in an electric fuse socket having a shell and a centerhcontact, a movable contact carrier having a central contact piece to connect the center contact of a plug with the center contact of the socket, and an actuator adapted to be located within the socket shell below the contact carrier and having means urging the latter outward to break the socket circuit in absence of a plug therein. l

4. For use in an electric fuse socket having a shell and a center contact, a movable contact carrier having a central contact piece to connect the center contact of a plug with the center contact of theA socket, and an actuator adapted to be located within the socket shell below the contact carrier and having means urging the latter outward to break the socket circuit in absence of a plug therein, the circuit being closed by downward movement of the contact carrier. actuated by insertion of a plug.

5. For use in an electric fuse socket having a shell and a center contact, a contact fcarrier arranged for axial movement within the shell and having a central contact piece to connect the center contact of a plug with the center contact of-the socket, the contact carrier being located to substantially close a slot in the shellwall and obstruct the insertion of an object therethrough to bridge the socket terminals.

6. For use in an electric fuse socket having a shell and a center contact, a movable contact carrier having a central contact piece to connect the center contact of a plug with the' center contact of the socket, and an actuator adapted to be located within the socket shell below the contact carrier and having means urging the latter outward to break the socket' circuit in abunder the action of said spring.

sence of a plug therein, said actuator comprising an annular disc having spring fingers for operating the.contact carrier.

'7. For use in an electric fuse socket having -a shell and a center contact, a movablecontact carrier having a central contact piece to connect function is accomplished y the center contact of a plug with the center contact of the socket, and an actuator adapted to be located within the socket shell below the contact carrier and having means urging the latter outward to break the socket circuit in absence of a 5 plug therein, said actuator comprising an annular disc having spring lingers for operating the contact carrier, and means retaining the contact carrier in the socket shell.

In combination with a socket of character set forth, an adapter including a lower portion substantially blocking an opening inthe socket shell and interfering with insertion of an object therethrough to bridge the socket contacts, and a circuit breaker in the adapter. j y

-9. In combination with a socket of character set forth, an adapter including a lower portion substantially blocking an opening in the socket shell and. interfering with insertion of an object therethrough to bridge the socket contacts, and a circuit breaker in. the adapter, said circuit breaker including a movable contact piece, and a resilient actuator thereunder.

10. In combination with a socket of character set forth, an adapter including a lower portion substantially blocking an opening in the socket shell and interfering with insertion of an object therethrough to bridge the socket contacts, and a circuit breaker in the adapter, said ciri cuit breaker including a movable contact piece, and a resilient actuator thereunder, and means preventing removal of said contact piece.

1l. In combination with a socket as described,

a disc of insulating materialginsertble therein and ,adapted for axial movement within the socket and having a concave outer surface and a contact piece passing centrally through the disc and having its outward end near the bottom of said cupped surface, whereby to prevent bridging from a surrounding shell surface to said center contact, and means for limiting the movement of said disk away from the bottom of said socket.

I2. In combination withy an electric socket of the character described including a metal screw `shell and a center contact, a disk of insulating material retained for moderate axial movement within the shell near the bottom thereof andhaving at its center a metal contact piece extending through the disk vand arranged for engagement with the center contact of the socket and with the center contact of an ordinary plug inserted in the socket shell, spring means normally urging the disk to outward position with its contact piece spaced from the center contact of the socket, and

l means for limiting the outward'movement of said 56 13. In y,combination with an electric socket of the character described including a metal screw shell and a center contact, a disk of insulating material retained for moderate axial movement o0 within the shell near the bottom thereof and hav--y ing at its center a metal contact piece extending through the disk and arranged for engagement with the center contact of the socket and with the center contact of an ordinary plug inserted o6 in the socket shell, a spring acting between the shell bottom and the disk and normally urging the disk to outward position and a stop means for determining the outward position of said disk 14. For use in an electric socket of character described including a metal screw shell and a center contact, an adapter insertable in the shell and including a substantially cylindrical threaded shell,and.wlthinthe adapteishellnearthebot- 1I described including a metal screw shell and a center contact, an adapter insertable in the shell and including a substantially cylindrical threaded shell, and within the adapter shell near the bottom thereof a disk'of insulating material retained for slight axial movement, the disk having at its center a contact piece extending through it and arranged for engagement with the socket center contact and the center contact of an ordinary plug inserted in the adapter shell, the bottom of the adapter shell being open to permit engagement of the disk contact with-the socket center contact.

16. For use in a'n electric socket of character described including a metal screw shell and a center contact, an adapter insertable in the shell and including a substantially cylindrical threaded shell, and within the adapter shell near the bottom thereof a disk of insulating material retained for slight axial movement, the disk having at its center a contact piece extending through it and arranged for engagement with the socket center contact and the center contact of an ordinary plug inserted in the adapter shell, and spring means intermediate the bottom portion of the adapter shell and the disk and normally urging the disk to outward position.

17. For use in an electric socket of character described including 'a metal screw shell and a center contact, an adapter insertable in the shell and including a substantially cylindrical threaded shell, and within the adapter shell near the bottom thereof a disk of insulating material retained for slight axial movement, the disk having at its center a contact piece extending through it and arranged for engagement with. the socket center contact and the center contact of an ordinary plug inserted in the adapter shell, the adapter shell having at' its bottom an inturned flange, and 5 spring means intermediate the flange `and. the disk and normally urging the latter to outward position.

18. In combination with an electric socket of the character described including a metal screw shell and a center contact, a disk of insulating material retained for moderate axial movement within the shell near the bottom thereof and having at its center a metal contact piece extending through the disk and arranged for engagement with the center contact of the socket and with the center socket of an ordinary plug inserted in the socket shell, and spring means normally urging the disk to outward position with its .contact piece l spaced from the center contact of the socket. the disk having its outer face concaved to prevent shorting by insertion of a simple metal object and to permit engagement of the center contact of an ordinary plug with the disk contact piece.

19. For' use in an electric socket of character 25 described including a metal screw shell and a center contact, an adapter insertable in the shell and including a substantially cylindrical threaded shell, and within the adapter shell near the bottom thereof a disk of insulating material retained for slight axial movement, the disk having at its center a contact piece extending through it and arranged for engagement with the socket center contact and thel center contact of an ordinary plug inserted in the adapter shell, the disk having its outer face concaved to prevent short-l ing by insertion of a simple metal object and to permit engagement of the center contact of the plug with the disk contact piece.

LAMBERT SCHMIDT, JR. 

